The present invention relates to a web guide roller for a web-fed rotary printing press. The print carrying web is guided over a driveable web guide roller with its printed side in contact with the web guide roller. The printed surface of the web is not smudged.
A web-fed rotary printing press is known from DE 29 51 246 C2. This prior device has at least one paper guide roller for reversing the paper web downstream of the last print unit in the running direction.
When the printed side of the paper web comes into contact with the paper guide roller, ink deposits occur on the paper guide roller, which can result in smudging of the printed image.
JP-A-57-193368 describes guide rollers whose diameter is equal to the diameter of a rubber blanket cylinder of a print unit.
The object of the present invention is based on providing a web guide roller.
In accordance with the present invention, the object is attained by the provision of at least one driveable web guide roller whose surface contacts the printed side of the print carrying web. The size of the web guide roller, and its rotational speed are selected so that there is no smudging of the print image on the print carrying web as it comes in contact with the web guiding roller.
The advantages which can be achieved by the present invention consist, in particular, in that the printed print-carrying web does not cause any deposit of printing ink on the web guide roller and therefore no smudging of the print image occurs when the printed web comes into contact with the web guide roller. This is achieved, on the one hand, by an oleophobic surface, for example made of chromium of the web guide roller, and on the other hand in that the web guide roller has an oleophilic surface such as a rubber packing or rubber cover. Thus, possible ink deposits on the surface of the web guide roller now occur harmlessly always at the same location.